Indoor Moss Microbial Fuel Cell

by braydennoh

14K22648

Intro: Indoor Moss Microbial Fuel Cell

I have been studying electrochemistry for some years and one day, I discovered something fascinating. I read a paper that showed that plants could be used to generate electrical power. Now, the mechanism behind how it works is a bit complex and some knowledge in chemistry is needed. Organic oxidation and reduction of bacteria cause potential differences and stores energy, just like capacitors. If you want to know more about the chemical process look at https://royalsocietypublishing.org/doi/full/10.10....

The thing is, making these plant fuel cells are crazy simple! So I am here to show you how to make your plant fuel cell. The research uses moss, which blew my mind off first because these plants don't have roots!

STEP 1: Get Some Moss!

First, you need some moss. I live near a creek, so it was easy for me to get some samples. If you live in a city or places where there is no excess to natural moss, Amazon sells preserved moss. You might be asking what type of moss should you get. I don't know! But that is where the potential of this project comes from. Many people can experiment with mosses from their region to determine which types of moss are best for the fuel cells. I am pretty sure my samples are feather moss. If you get your moss from outside, make sure you wash them several times.

STEP 2: Step by Step

Second, you need the materials. Now, compare to other projects, the things needed for this project are a bit foreign, but not too expensive. You will use carbon or graphite felt (carbon felt is cheaper) for the anode of the cell. For the cathode, you will need aluminum foil. The fuel cell needs dielectric and I am using zeolite powder, which is usually used for cosmetics. So the two weird materials are carbon felt and zeolite powder.

Step 1: Get or make a box for storing all the components. The bottom needs small holes. Make sure the height of the box is at least 2 cm. I had some 3d printed scraps around the house, so that explains the many tape marks on the box.

Step 2: Cut an aluminum foil that matches the size of the box and place it on the bottom. If the aluminum foil is creeping up the wall, duct tape it so it won't touch the anode in the future.

Step 3: Get one cable and tape it on the aluminum. I used copper tape, so the top side would also be conductive.

Step 4: Place the zeolite powder on top of the aluminum foil. I used 1.5 ounces to cover up a 12 cm x 12 cm squared box. The height of the zeolite volume was about 0.6 cm.

Step 5: Place the carbon or graphite felt on top of the powder. Make sure that the aluminum foil does not contact the graphite felt! Also, place a wire on top of the felt. Make sure you don't place the wire at the bottom.

Step 6: Get some soil from the backyard and moisture it. The height of the covering soil was about 0.3 cm. Next, place the moss on top of the moisturized soil and pressure it gently.

STEP 3: Done!

That is it! It's almost like making a sandwich. Now the experimentation is all upon you. Change the moss breed, sunlight, humidity to see the changes in voltage. It's like taking care of plants but you will get numbered output based on the performance. How cool is that?

STEP 4: My Build

Don't expect too much from the fuel cell. Remember, it is just moss. From the 0.0144 meters squared area of moss, I have been getting about 0.8 V with fluorescent light. This resulting power output is in the range entering milliwatt (mW). But I think there are potentials of this technology in building rooftops. Imagine harvesting energy from the garden instead of solar panels!

Thanks for viewing - Brayden Noh

STEP 5: Video of the Fuel Cell Charging


32 Comments

RichardD263 2 years ago

Here's A PSA for anybody starting this project. I hope this will clear up some of the previous questions. Obviously this website is for the casual DIY'er so I'll try to write clearly; feel free to ask clarifying questions and I will answer as best I can.

I am a student in California and was inspired by this Instructable to research this process- about a year ago. I'll preface this with my experience: I am working towards a career in research and am in the process of publishing a previous study of which I am the sole author. I do not yet have a degree but I worked with a professor near me from California Polytechnic University to analyze this cell design. In short, I will share what I have learned from this long-term project; but I am not a working professional in this field. Feel free to correct any misconceptions I may present, I appreciate the help.

If you are like me and want to use microbes to generate power on a small, DIY scale (like this Instructable's design), then this is not the place to start. I read a LOT of studies on the subject and began with several iterations of this specific plan as presented in the images above, using zeolite, carbon felt from fireproof blankets, and aluminum foil. I thought that this design with the moss would somehow be more effective than the other moss-less designs out there. I tracked the progression of one of these cells over the course of a few weeks, and reached a peak voltage of 0.56V and a peak current of 15 micro-Amps (15E-6 A). Power is voltage times current, and thus this produces negligible usable power in Watts. These measurements did not stem from the moss- they, as suggested in other comments, came from the chemical reaction of the aluminum and carbon electrodes. In order to utilize the bacteria and microbes to create current, they need up to several weeks to grow and position themselves in a conductive layer where they can create free electrons through biological processes. This happens more quickly and easily in a cell saturated with water! Thus, many designs use microbes from wastewater and use no soil or substrate at all.

The tried and true method for making microbial fuel cells is to place the two electrodes directly in the soil substrate or wastewater. My current design uses an aluminum plate with soil substrate and carbon felt on top, and I have read currents of around 200 micro-Amps- an order of magnitude larger than the old design. Using four small (1"x2") cells of this type wired in series, the chemical potential reached 1.5V, which leads me to believe that improving the efficiency of the cells even on a small scale could make them produce useable power.

I intend to further study the use of moss in this application. My running theory is that the moss could 1) bring more diverse microbes and 2) produce oxygen in a sealed cell. However, I have concluded that this cell type is far and away more complicated on a DIY scale than other options. Let me know if anyone has other readings or successes; I may compile my findings in a short academic paper in which case I will link it here.

thearedulla 1 year ago

Hi! I am also a student that is interested in your knowledge, and I initially planned on using the design that was shared in this post, that is until I saw your comment. I would like to know more about your design in detail, how you managed to choose materials accordingly, and their purpose in your study. Do you continue to use zeolite as dielectric, like what was stated in this post?

martinayumin 1 year ago

I am a student in Korea that is planning on a project, using moss to generate power(in any way). Could you recommend a (fairly) simple way to prevent what you pointed out - the energy coming from the chemical reaction between aluminum and carbon electrodes - without changing the entire build of this project?

RichardD263 1 year ago

Hello! The main takeaway from my time studying this design is that the model shown here does not make power using moss; in fact, the energy in a plant microbial fuel cell comes from the microbes, not the plants. I would recommend reading studies concerning "plant microbial fuel cells" and trying to determine which models could use moss.
Speaking to what you asked about a simple way to prevent the aluminum-air properties from interfering- using two inert electrodes allows you to measure the power generated by the microbe population. This could be two carbon felt electrodes, graphite rods, etc.
Let me know how your project goes, I'd be fascinated to hear how the next stage of research on the topic goes, and I'd be happy to answer any other questions you may have to the best of my ability!

martinayumin 1 year ago

Thanks a lot for the help, and the quick relply! I'll be sure to let you know when we've made progress, positive or otherwise.

Saathvik 2 years ago

Does the carbon filter pads used in air purifier also work? or i specifically need to pick some kind of carbon felt

kevin413 3 years ago

Hi! measured the voltage without the moss and soil planted and got a read of around 0.9V. What might be an explanation for this?

matthdi 2 years ago

With or without the moss and soil: the graphite, the wet zeoilte and the aluminum foil make up a perfect aluminum-air battery. That's where your voltage comes from.

JosephU10 2 years ago

An analogy that I hope is helpful and not too long winded.

If you imagine walking out of a store on a hot day and the air rushing against your face is a combination of the difference in temperature. The bigger the difference in the temperature the faster the air potential tries to make up the hap. The more dense the air the easier it is to both feel and combined with the speed of the air trying to fill the temperature gap becomes the force that you can feel.

In this case you are measuring voltage which is similar to the temperature difference. The difference in the electrical charge provides that sort of gap that wants to be filled. But you not only need the voltage difference (i.e. difference in temperature) to be useful you also need the amperage (i.e. Air density) to produce some actual that you can measure as watts (i.e. pushing force).

For your case I think what you were measuring was mostly the difference in potential voltage between the graphite and the aluminum. But the amps are likely at a trickle and not useful to actually power something. To get the amps to flow you need to be moving charge between the two areas and for that the bio processes mentioned help. So with the moss, soil, moisture, light etc... you probably would measure more amps.

You get watts of power by multiplying the Amps and the Voltage together.

Its kind of like having an upside down 2 liter water bottle with a tiny bit of water left on the sides. The potential angle is the same (i.e. voltage) but your not going to be able to move a water wheel unless you have a decent amount of water (i.e. amps) moving from the top of the bottle out the spout. The bio processes kind of generate that preverbal water that can flow out that bottle.

ludwigtiston 3 years ago

What kind of zeolite is required for this, online I find zeolite for aquarium purification and as a dietary supplement and such. Does this: https://www.heiltropfen.de/shop/en/home/18-zeolite... work for example?
Also, what other materials work for this, that is to say; what qualities of the zeolite are we looking for here? Very interesting project I must say!

MsJenfaM 3 years ago

I'm a classroom teacher interested in doing this with my students. I read all the replies but some people didn't get it to work. Does it for sure work??? What about water? Can you use other plants?

braydennoh 3 years ago

Zeolite might be too expensive for classroom uses. I would rather recommend doing things with hydrogen fuel cell or mud fuel cell.

MsJenfaM 3 years ago

Hm, sounds cool. I don't live in the US...

Megan_Gill 3 years ago

Thank you for this Instructable! It is really interesting. I have attempted to build a couple of these but am not getting any voltage. Does the zeolite clay have to be moistened or kept dry? Thank you.

jazminekimchi 3 years ago

omg this is literally insaaaaane !!!! can i ask if does seaweed works just fine as an alternative to moss ?

JacenF 3 years ago

How much did it cost?

bronyeg 3 years ago

Hey, you should go to mars someday, but just scratching my head for answers what does the moss do exactly, I'm kinda confused on this and i am hoping to make a larger one to maybe power a bunch of LEDs for a fun demonstration, and I need to sound nerdy. :-D to live up to my name.

ThLinn 3 years ago

Id like to know if you have ever herd of batch Bio digesters and if so have you ever tried to build one? there have been some built by farmers in the US but they use tanks that are far from the optimal design. The Japans have been building a sqaushed ball tank version for many years that is a true God send in all its benifits. Much of which comes from the symple changing of the shape of the tanks.
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